package com.question.java.date7;

import java.text.SimpleDateFormat;
import java.util.Calendar;

/**
 * @Description:
 * @Author: Jun Yang
 * @Time: 2019/1/20 下午3:10
 * @Version: 1.0
 */
public class DateUtils {
    public static void main(String[] args) {
        SimpleDateFormat format = new SimpleDateFormat("yyyy-MM-dd");

        //获取前月的第一天
        Calendar cal_1=Calendar.getInstance();//获取当前日期
        cal_1.add(Calendar.MONTH, -1);
        cal_1.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天
        String firstDay = format.format(cal_1.getTime());
        System.out.println("-----1------firstDay:"+firstDay);

        //获取前月的最后一天
        Calendar cale = Calendar.getInstance();
        cale.set(Calendar.DAY_OF_MONTH,0);//设置为1号,当前日期既为本月第一天
        String lastDay = format.format(cale.getTime());
        System.out.println("-----2------lastDay:"+lastDay);


        //获取当前月第一天：
        Calendar c = Calendar.getInstance();
        c.add(Calendar.MONTH, 0);
        c.set(Calendar.DAY_OF_MONTH,1);//设置为1号,当前日期既为本月第一天
        String first = format.format(c.getTime());
        System.out.println("===============first:"+first);

        //获取当前月最后一天
        Calendar ca = Calendar.getInstance();
        ca.set(Calendar.DAY_OF_MONTH, ca.getActualMaximum(Calendar.DAY_OF_MONTH));
        String last = format.format(ca.getTime());
        System.out.println("===============last:"+last);

    }
}
